falcon

Rules / Correctness / correct-order-for-super-dispose

correct-order-for-super-dispose

lint/correctness/correct-order-for-super-dispose
recommendedflutter
Same as correct_order_for_super_dispose · Pyramid Lint

Require super.dispose() to be the last call in dispose.

Flags a super.dispose() invocation that is not the final statement of a dispose method. The base State.dispose tears down the framework's own bookkeeping for the object, after which touching the widget's fields is unsafe, so any cleanup your subclass performs must happen first. A super.dispose() in the middle of the method leaves the remaining cleanup running against a half-disposed object. Move the super.dispose() call to the end.

Invalid

example.dartdart
import 'package:flutter/material.dart';

/// Calling super.dispose before cleanup
class BadDisposeOrder extends ChangeNotifier {
  late AnimationController controller;
  late StreamSubscription subscription;

  @override
  void dispose() {
    super.dispose();
    controller.dispose();
    subscription.cancel();
  }
}

/// Another bad example
class AnotherBadDispose extends ChangeNotifier {
  late TextEditingController textController;
  late FocusNode focusNode;

  @override
  void dispose() {
    super.dispose();
    textController.dispose();
    focusNode.dispose();
  }
}

/// Multiple resources with super called first
class MultipleResourceDispose extends ChangeNotifier {
  late StreamController streamController;
  late Timer timer;

  @override
  void dispose() {
    super.dispose();
    streamController.close();
    timer.cancel();
  }
}

/// Bad: super.dispose in middle
class MiddleDispose extends ChangeNotifier {
  late ScrollController scrollController;

  @override
  void dispose() {
    scrollController.dispose();
    super.dispose();
    print('cleanup done');
  }
}

/// Bad: early super call with multiple cleanups
class EarlySuper extends ChangeNotifier {
  late PageController pageController;
  late TabController tabController;

  @override
  void dispose() {
    super.dispose();
    pageController.dispose();
    tabController.dispose();
  }
}
super.dispose() should be called last in the dispose method.
9 void dispose() {
10 super.dispose();
super.dispose() should be called last in the dispose method.
22 void dispose() {
23 super.dispose();
super.dispose() should be called last in the dispose method.
35 void dispose() {
36 super.dispose();
super.dispose() should be called last in the dispose method.
48 scrollController.dispose();
49 super.dispose();
super.dispose() should be called last in the dispose method.
60 void dispose() {
61 super.dispose();

Valid

example.dartdart
import 'package:flutter/material.dart';

/// Cleanup before calling super.dispose
class GoodDisposeOrder extends ChangeNotifier {
  late AnimationController controller;
  late StreamSubscription subscription;

  @override
  void dispose() {
    controller.dispose();
    subscription.cancel();
    super.dispose();
  }
}

/// Another good example
class AnotherGoodDispose extends ChangeNotifier {
  late TextEditingController textController;
  late FocusNode focusNode;

  @override
  void dispose() {
    textController.dispose();
    focusNode.dispose();
    super.dispose();
  }
}

/// Multiple resources with correct order
class MultipleResourceDispose extends ChangeNotifier {
  late StreamController streamController;
  late Timer timer;

  @override
  void dispose() {
    streamController.close();
    timer.cancel();
    super.dispose();
  }
}

/// Single resource cleanup
class SingleResourceDispose extends ChangeNotifier {
  late AnimationController animation;

  @override
  void dispose() {
    animation.dispose();
    super.dispose();
  }
}

/// Good: cleanup with super at end
class ScrollDispose extends ChangeNotifier {
  late ScrollController scrollController;

  @override
  void dispose() {
    scrollController.dispose();
    super.dispose();
  }
}

/// Good: multiple cleanup steps then super
class ComplexDispose extends ChangeNotifier {
  late PageController pageController;
  late TabController tabController;
  late StreamSubscription streamSub;

  @override
  void dispose() {
    pageController.dispose();
    tabController.dispose();
    streamSub.cancel();
    super.dispose();
  }
}

How to configure

Set the severity of correct-order-for-super-dispose in your falcon.json:

falcon.jsonjson
{
  "linter": {
    "rules": {
      "correctness": {
        "correct-order-for-super-dispose": "error"
      }
    }
  }
}

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